首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5689篇
  免费   199篇
  国内免费   9篇
电工技术   36篇
综合类   4篇
化学工业   956篇
金属工艺   57篇
机械仪表   76篇
建筑科学   258篇
矿业工程   31篇
能源动力   61篇
轻工业   776篇
水利工程   48篇
石油天然气   40篇
无线电   226篇
一般工业技术   683篇
冶金工业   1926篇
原子能技术   12篇
自动化技术   707篇
  2023年   28篇
  2022年   68篇
  2021年   93篇
  2020年   59篇
  2019年   79篇
  2018年   92篇
  2017年   97篇
  2016年   97篇
  2015年   81篇
  2014年   125篇
  2013年   339篇
  2012年   198篇
  2011年   321篇
  2010年   228篇
  2009年   235篇
  2008年   261篇
  2007年   277篇
  2006年   236篇
  2005年   201篇
  2004年   175篇
  2003年   175篇
  2002年   174篇
  2001年   102篇
  2000年   111篇
  1999年   107篇
  1998年   90篇
  1997年   102篇
  1996年   124篇
  1995年   89篇
  1994年   107篇
  1993年   123篇
  1992年   105篇
  1991年   45篇
  1990年   99篇
  1989年   102篇
  1988年   72篇
  1987年   88篇
  1986年   84篇
  1985年   86篇
  1984年   64篇
  1983年   65篇
  1982年   46篇
  1981年   52篇
  1980年   42篇
  1979年   42篇
  1978年   27篇
  1977年   42篇
  1976年   24篇
  1975年   34篇
  1974年   24篇
排序方式: 共有5897条查询结果,搜索用时 15 毫秒
21.
The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bilayer configurations were determined; these water binding/migration properties were related to the mechanical characteristics of the gels. Samples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20–60 min. Moisture migration rates from samples interfaced with filters were determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxial compression and microscopy. Results showed that gel strength and consequent extent of protein interaction—as affected by thermal treatment—controlled the ability of the gel structure to absorb water. Sorption was exponentially correlated with gel modulus and linearly correlated with a function of protein content, heating time, and immersion time. Rates of diffusion from interfaced gels were dependent solely on water content. It was concluded that the degree of protein interaction, whether influenced by concentration or thermal treatment, affected network extensibility and thus the capacity of the gels to act as receptors of moisture. Results have implications for the functionality of shelf-stable sandwiches and other multicomponent foods.  相似文献   
22.
23.
A stability-indicating high-performance liquid chromatography for the quantitation of cefaclor in pharmaceutical dosage forms has been developed. The method is accurate and precise with a percent relative standard deviation of 1.2 based on 5 readings. A number of inactive ingredients present in the capsules and suspensions did not interfere with the assay procedure. The extraction procedure from the dosage forms is very simple. The recovery from the synthetic mixtures was quantitative. The capsules which had expired 3 years ago lost only 3% of the potency. The drug appears to be very sensitive to strong acids or bases since a 5 minute boiling caused 100% degradation of drug in both the solutions.  相似文献   
24.
Increased adoption of empirically supported treatments (ESTs) has been hindered in part by inadequate and inconvenient access to EST information and training. To improve diffusion of ESTs, the authors developed a Web application to provide practitioners with concise information by disorder on ESTs. The resulting site, therapyadvisor.com, was evaluated by 239 practicing psychologists to assess the usefulness of the site and explore possible interactions of EST attitudes on ratings of usefulness and impact. Two thirds of participants indicated using ESTs in practice, and limited time and resources were cited as primary barriers to EST adoption. The Web application was rated positively by most participants and was reported to increase awareness of and commitment to try ESTs among approximately 60% of participants. The results of this project support the feasibility of a Web application to increase diffusion and promote further adoption of ESTs. Technological and e-learning advances are promising directions for encouraging the adoption of ESTs specifically and evidence-based practice generally, particularly among busy practitioners who have inadequate time and resources for more traditional forms of dissemination and training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
25.
This study examined (1) predictors of treatment outcome for opioid-dependent participants in a single-site controlled trial comparing methadone, buprenorphine, and LAAM treatments and (2) the extent to which various subpopulations of patients may have more successful outcomes with each medication. The relationships between patient demographics, drug use history, and psychological status and outcome measures of treatment retention, opiate use, and cocaine use were assessed. We believe this study to be the first to demonstrate that predictors of treatment success appear to be largely similar in LAAM, buprenorphine, and methadone treatment for opioid dependence. We did not find any factors that would strongly guide selection of one medication over others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
26.
27.
Eye movements during natural tasks suggest that observers do not use working memory to capacity but instead use eye movements to acquire relevant information immediately before needed. Results here however, show that this strategy is sensitive to memory load and to observers' expectations about what information will be relevant. Depending upon the predictability of what object features would be needed in a brick sorting task, subjects spontaneously modulated the order in which they sampled and stored visual information using working memory more when the task was predictable and reverting to a just-in-time strategy when the task was unpredictable and the memory load was higher. This self organization was evidenced by subjects' sequence of eye movements and also their sorting decisions following missed feature changes. These results reveal that attentional selection, fixations, and use of working memory reflect a dynamic optimization with respect to a set of constraints, such as task predictablity and memory load. They also reveal that change blindness depends critically on the local task context, by virtue of its influence on the information selected for storage in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
目前,低成本手机数量不断增多,市场份额越来越大,比高端手机更受欢迎。研究表明,未来三年,低成本手机市场还将持续增长,这将是无线产业最主要的发展趋势之一,已经并将继续为无线手机制造商、服务供应商及芯片设计商带来金融、市场、战略和技术领域的重大变革与挑战。  相似文献   
29.
In target detection tasks, responses are faster when displays have 2 targets (redundant-targets effect; RTE) and slower when they have no targets (nontargets effect; NTE) relative to displays with a single target. The psychological refractory period paradigm was used to localize these effects. In Experiment 1, participants classified tones as high or low and then classified letters as targets or nontargets after a short or long stimulus onset asynchrony (SOA). The magnitudes of the RTE and NTE did not depend on SOA. In Experiment 2, the order of the tasks was reversed, and at short SOAs the RTE and NTE had similar magnitudes for both tone discrimination and target detection responses. These findings suggest that the RTE and NTE arise during response selection. Interactive effects of tone pitch with the number and type of target features were also observed, and these were tentatively interpreted as synesthetic effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
30.
The definition of an empirically supported treatment (EST) arguably embodies 2 untested assumptions: (a) that different manualized renditions of the same therapy are functionally equivalent and (b) that therapies can be reliably applied independently of therapist, setting, and format. These assumptions were tested as applied to cognitive therapy (CT), using process data from a large multisite study (N=235) that included 3 cognitive and 6 alternative therapies. Although the non-CTs were more variable than the CTs on 2 of 4 dimensions studied (directiveness and emotional arousal), there was considerable variation among the 3 CTs, even when implemented in the current context of rigorous training, manualization, and adherence checks. Results are discussed as related to the assumptions underlying EST criteria. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号